Biologist’s ‘no-regret strategies’ seek to protect the planet with seaweed

For the past several months, Carlos Drews, a biologist and executive vice-president of conservation for Vancouver-based environmental organization Ocean Wise, has been trying to figure out how to transform barren bits of B.C. seafloor into vibrant forests of kelp that sequester carbon and bolster biodiversity. These forests were common in the waters off B.C. before fur traders extirpated its sea otters in the early 20th century.

With the sea otters gone, their main prey — kelp-eating sea urchins — flourished, decimating kelp forests by between 40 and 60 per cent as the population boomed. That "alarming" loss of the "home of so much marine life" also reduced the ocean's capacity for absorbing greenhouse gas emissions. Seaweed is an "incredible carbon sink" that can help move planet-warming pollution from the atmosphere to the deepest parts of the sea, Drews explained.

That balance could soon start to shift. Sea otters have recently started returning to B.C. waters, raising hope they could help keep the urchins in check enough to let kelp forests grow back.

Drews and his team are trying to make those oceanic forests regenerate even faster — but it's a tricky task. They have tried everything from coaxing baby seaweed to grow on pebbles to gluing spores to the seafloor.

Kelp has been farmed in Asia for centuries, but these farming techniques aren't very useful for restoring seaweed forests, he explained. Kelp farmers grow the seaweed on ropes suspended in the water, making it relatively easy to protect the developing algae from ocean currents, storms, warming waters and predators.

Drews and his team can't afford to protect their kelp babies that much. Ocean Wise is hoping that one day it will be able to help First Nations and other groups restore kelp forests in hundreds of places across the B.C. coast. Drews said these efforts could also generate enough carbon offset and biodiversity credits to fund future kelp restoration and farming projects.

Demand for these credits is poised to be high as companies try to offset their environmental impact. Late last year, a Japanese company successfully sold kelp-based carbon credits certified by the Japanese government for about $735 per tonne of carbon — far higher than most other types of credits.

Those efforts aren't without controversy. B.C. has a vibrant fishery for sea urchin, whose roe is beloved by sushi aficionados and can fetch a handsome price. Critics have also pointed out that a lack of transparency in carbon markets — particularly the so-called "voluntary" market, which is commonly used but unregulated — means that in some cases, they do little more than help companies greenwash their operations.

Despite the critiques, Drews said restoring kelp forests is essential to protecting both the climate and biodiversity.

"We need to draw down (carbon) quickly," he said. "We cannot have paralysis now. Now is the time to be learning by doing, with no-regret strategies, as in (they) cannot possibly be worse than what we have before us in terms of climate change."

Still, the scale of restoration will only be possible if they can find a simple and affordable way to ensure their kelp babies survive.

Holding a teenage frond of kelp up to the April sun at the organization's research centre in West Vancouver, the biologist said his team is at the cusp of success. An experiment last fall where the team dropped gravel inoculated with baby kelp onto the seabed near Bamfield, B.C., triggered the growth of a "full-blown" kelp forest.

"It was a line of kelp forest three metres tall. There were octopus, there were the beautiful sea stars — (this technique) works," he said.